An invalid-free flaw was found in the way OpenSSL handled certain DTLS handshake messages. A malicious DTLS client or server could send a specially crafted message to the peer, which could cause the application to crash or potentially result in arbitrary code execution.

The following was reported by OpenSSL upstream:
This vulnerability does not affect current versions of OpenSSL. It existed in previous OpenSSL versions and was fixed in June 2014.
If a DTLS peer receives application data between the ChangeCipherSpec and Finished messages, buffering of such data may cause an invalid free, resulting in a segmentation fault or potentially, memory corruption.
This issue affected older OpenSSL versions 1.0.1, 1.0.0 and 0.9.8.
OpenSSL 0.9.8 DTLS users should upgrade to 0.9.8za
OpenSSL 1.0.0 DTLS users should upgrade to 1.0.0m.
OpenSSL 1.0.1 DTLS users should upgrade to 1.0.1h.
This issue was originally reported on March 28th 2014 in https://rt.openssl.org/Ticket/Display.html?id=3286 by Praveen Kariyanahalli, and subsequently by Ivan Fratric and Felix Groebert (Google). A fix was developed by zhu qun-ying.
Acknowledgements:
Red Hat would like to thank the OpenSSL project for reporting this issue.